ObjectivesThe aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram). Material and methodsTwenty cylinders (5 mm diameter and 4 mm height) of each composite were randomly allocated to 4 groups (n=5), according to the food-simulating liquid in which they were immersed for 7 days at 37ºC: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load). Measurements of the surface roughness (Ra, µm) were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM). ResultsThe statistical analysis (ANOVA with cofactor / Tukey's test, α=5%) detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. ConclusionsThe surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media.

The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

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À minha grande amiga Claudia, "Minha companheira desde o início desta caminhada. Nossa amizade está baseada na cumplicidade dos momentos que sempre dividimos em verdadeira sintonia, quer fossem momentos de alegria ou de dificuldade. Somos exemplo de pessoas que se querem bem, que se estimam verdadeiramente, que se respeitam. A sua alegria, a sua bondade, sempre me contagiou, incentivou e me permite dizer que as verdadeiras amizades existem sim! Eu, particularmente, faço questão de preservar nossa amizade, para sempre! E, apesar da distância, desejo que você seja sempre muito feliz! E tenha muito sucesso! Ao longo de nossa vida muitos amigos passam por ela e nos deixam saudade, mas também deixam a recordação de tudo que foi vivido. É na amizade verdadeira que encontramos sinceridade, lealdade, afinidade, cumplicidade, simplicidade, fraternidade. Amigos são irmãos que a vida nos deu para caminhar conosco ao longo da nossa jornada espiritual, extrapolando os limites do tempo, continuando quando e onde Deus assim o permitir.